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June 28, 1955 w. G. LEGGE 2,712,093

BODY GROUNDING DEVICES Filed Jan. 3, 1952 4 Sheets-Sheet l pglg zlmmzlzm gnmnmmm IN VEN TOR. 146a r51? 6. L'fifi yam/54;

June 28, 1955 I w, LEGGE 2,712,098

BODY GROUNDING DEVICES 4' Shee ts-Sheet 3 Filed Jan. 5, 1952 ray l'fOPA/E/S June 28, 1955 w. G. LEGGE BODY GROUNDING DEVICES Filed Jan. 3, 1952 4 Sheets-Sheet 4 III" I40 37 ZZ 134 INVENTOR. W44 r64? 6. LE6 Q6 BY fiwdd United States Patent i 2,712,098 B01)? GROUNDING DEVICES Walter G. Legge, Brooklyn, N. Y. Application January 3, 1952, Serial No. 264,818 4 Claims. (Cl. 317-2) This invention relates to a grounding device for conducting electrostatic charges from the human body to the ground or supporting surface on which the individual is standing or walking.

Grounding devices of this character provide protection for workmen engaged in the handling or treatment of explosive materials and gases and inflammable substances and liquids which are readily ignited by an electrostatic spark. Such grounding devices have proved unsatisfactory, however, due to the fact that they have been loose fitting and cumbersome which has hampered and impeded the free movement of the Worker and which has rendered it dangerous to engage about operating machinery. Furthermore, the grounding devices have not provided the proper protection against conducting a high voltage current to the workman in the event the grounding member of the grounding device comes into contact with a source of high potential.

In order to overcome these objections, the present invention provides a grounding device which is adapted to engage about the leg of the wearer either above or below the knee and with a flexible conductor member including a tensioning device connecting the leg attaching means to a grounding member carried by a shoe, boot, I

overshoe and the like. By this construction the grounding device is retained in close parallel relation with the leg of the wearer so as to guard against interference with operating machinery which might endanger the worker and which by means of the tensioning device retains the flexible conductor member in taut condition at all times permitting of the expansion and contraction thereof with the movement of the foot of the worker.

Another object of the invention is to provide a grounding device with a resistor element located adjacent the shoe, boot, overshoe and the like and forming a part of the flexible conductor member which will prevent a high voltage electric charge from being conducted through the upper portion thereof which is adapted to contact with the leg of the workman to thereby prevent the workman from receiving an electric shock in the event that the grounding device comes in contact with a charged conductor or a source of high potential current.

Still another object of the invention is to provide a grounding device which will continually discharge static electricity as the same accumulates on the body of the workman so as to prevent accumulation of a sufiicient charge thereof to produce a spark which might ignite explosive or inflammable substances when any part of the body is momentarily grounded.

With the foregoing and other objects in view, reference is now made to the following specification and accompanying drawings in which the preferred embodiments of the invention are illustrated.

In the drawings:

Fig. l is a view in elevation of the grounding device applied to a shoe.

Fig. 2 is an enlarged under side view of the grounding member showing a fragmentary portion of the shoe.

Fig. 3 is a longitudinal sectional view taken approximately on line 33 of Fig. 2.

Fig. 4 is a similar view taken approximately on line 4--4 of Fig. 2.

Fig. 5 is a cr0ss-sectional view taken approximately on line 55 of Fig. 2.

Fig. 6 is an enlarged vertical sectional view through the tensioning device taken approximately on line 6-6 of Fig. l.

2,712,098 Patented June 28, 1955 Fig. 7 is an enlarged vertical sectional view through the resistor taken approximately .on line 7--7 of Fig. 1.

Fig. 8 is a plan view of the leg encircling member.

Fig. 9 is an under side view of a modified form of grounding member applied to a shoe fragmentarily shown.

Fig. 10 is an enlarged cross-sectional view taken approximately on line 1010 of Fig. 9.

Fig. l1 is an under side view of a further modified form of grounding member shown applied to a shoe which is fragmentarily shown.

Fig. 12 is a longitudinal sectional view taken approximately on line 1212 of Fig. 11.

Fig. 13 is a cross-sectional view taken approximately on line 13-13 of Fig. 11.

Fig. 14 is a cross-sectional view showing a further modified form of grounding member applied to a shoe shown in section.

Fig. 15 is a bottom plan view of the grounding member shown in Fig. 14.

' Fig. 16 is a view in elevation of a further modified form of grounding member applied to a shoe.

Fig. 17 is an enlarged cross-sectional view taken approximately on line 17-17 of Fig. 16.

Fig. 18 is a bottom plan view of the grounding member applied to a shoe which is fragmentarily shown.

Fig. 19 is a cross sectional view of a further modified form of grounding member applied to a rubber overshoe which is shown in section.

Fig. 20 is an enlarged crosssectional view taken approximately on line 20-20 of Fig. 19.

Fig. 21 is an under side view of the grounding member shown in Figs. 19 and 20.

Fig. 22 is a view in elevation of a further modified form of grounding device applied to a boot with the boot and grounding member shown partially in section.

Fig. 23 is an enlarged cross-sectional view taken approximately on line 2323 of Fig. 22.

Fig. 24 is an under side view of the grounding member shown in Figs. 22 and 23 applied to the boot which is fragmentarily shown.

Fig. 25 is a view in elevation of the grounding device applied to an article of foot covering for nurses and doctors.

Fig. 26 is a fragmentary vertical sectional view taken approximately on line 2626 of Fig. 25

Fig. 27 is a view in elevation of a modified form-of foot covering for nurses and doctors for use in conjunction with the grounding device.

Fig. 28 is a fragmentary vertical sectional view taken approximately on line 28-28 of Fig. 27.

Fig. 29 is a similar view showing a modified form of foot covering.

Referring to the drawings by characters of reference and more particularly to the form of the invention illustrated in Figs. 1 to 8 inclusive thereof, the grounding device indicated generally by the reference character 10 is adapted to be fastened to the leg of the wearer and includes a grounding member carried by a shoe, boot, overshoe and the like for conducting electrostatic charges from the body of the wearer to the ground. In order to provide an intimate contact with the leg of the wearer the grounding device includes a leg-encircling elastic band 11 which is affixed at one end to a flat metallic plate 12 and has a fastening element 13 secured to the opposite end thereof for releasably engaging a headed stud 14 for securing the band 11 in encircling relation about the" leg of the wearer with the metallic plate 12 tensioned flatly against the leg of the wearer so as to form a good electrical contact. The plate 12 is connected with a metallic grounding member 15 carried by the shoe, boot, overshoe and the like by means of a flexible conductor 16 consisting of a conductor wire or chain as illustrated, a resistor 17 and a tensioning device 18. The resistor 17 is connected with the grounding member by a short conductor section 19 and the resistor 17 and tensioning device 18 are connected together by a conductor section 20 and the tensioning device is connected with the metallic plate 12 by a conductor section 21.

The flexible conductor 16 is of a length to dispose the metallic plate 12 and the elastic band 11 above the knees for female workers and between the knee and the upper portion of the muscle below the knee for male workers in either of which locations the elastic band 11 provides the least discomfort to the wearer and is in an out-of-theway position whereby the same together with the conductor 16 extending substantially longitudinal with reference to the leg is not likely to become engaged in operating machinery so as to endanger the wearer. Furthermore, the tensioning device 18 retains the flexible conductor 16 in taut condition at all times and elongates and contracts with the movement of the leg of the wearer in walking.

The tensioning device 18 includes inner and outer telescopically arranged cylindrical tubes 22 and 23 formed with end loops 24 and 25 at the outer ends thereof which are linked with the conductor sections 21 and 20 respectively. A coil spring 26 is arranged within the telescopically associated sections and is connected with the end loops 24 and 25 thereof for maintaining the same in tensioned retracted relation and permitting of relative movement of the sections with reference to each other into tensioned elongated relation. The tension of the spring 26 is suflicient to maintain the conductor 16 in taut condition in close relation with the leg of the wearer so as to prevent sagging thereof which would render the same uncomfortable and possibly endanger the life of the wearer by engaging in operating machinery.

The resistor 17 is located adjacent the grounding member 15 below the top of the shoe, boot, overshoe and the like so that the conductor section 19 cannot come in contact with the leg of the wearer. The resistor is such that it prevents the passage of a sufliciently high current from the grounding member 15 to the portion of the flexible conductor 16 above the resistor which would endanger the life of the wearer in the event that the grounding member 15 came in contact with a high potential conductor. The resistor 1.7 includes a resistance wire 28 which is connected at its ends with the conductor sections 19 and 20 and is enclosed in an insulation covering 29. The resistance wire 28 is a safety fuse preferably having a resistance of 250,000 ohms which will prevent an excessive current flowing therethrough which might endanger the wearer in the event that the grounding member came into contact with a high potential conductor. However, the resistance 28 may vary from 25,000 to 500,000 ohms resistance depending upon the use to be made of the grounding device.

The grounding member 15 includes an adjustable clamp 31 consisting of oppositely disposed clamping portions 32 and 33 having upwardly extending inwardly directed ears 34 and 35 respectively which are adapted to clamp over the outer edges of the shoe sole indicated by the reference character A adjacent the heel B of a shoe C and the like. The clamping portions 32 and 33 are formed with aligned openings 36 and 37 which are right and left-hand threaded respectively for receiving the correspondingly threaded ends of a tightening screw 38 for adjusting the clamping portions 32 and 33 towards and away from each other by rotation of the screw 38 by engagement of a suitable tool on the rectangular shaped outer end 39 thereof for clamping the cars 34 and 35 against the shoe sole A or for removing the same therefrom. On opposite sides of the threaded openings 36 and 37 the clamping portions 32 and 33 are each formed with rectangular shaped slots 40 and 41 which open through the sides thereof below the ears 34 and 35 and which terminate in longitudinally extending dovetailed potions 42 and 43 espectively that open through the lower face of said clamping portions.

Contact members 44 of U-shaped formation in crosssectional configuration are provided having flat connecting portions 45 and upstanding side portions 46 and 47 which slidaoly fit the slots 46 and 41. The side portions 46 and 47 are formed with dove-tailed upper ends 48 and 49 respectively corresponding to the shape of the lower portions 42 and 43 of said slots for retaining the contact members in the slots. The contact members protrude below the heel B of the shoe and are tensioned by any desired means such as by leaf springs St to insure the connecting portions 45 making positive contact with the supporting surface. The contact members are slidable into position in the slots through the ends thereof and are maintained in position therein by cross pins 51. When applied to a shoe, boot, overshoe and the like, the ear 35 of the grounding member 15 is preferably clamped against the outer side edge of the shoe sole with the conductor section 19 of the flexible conductor 16 secured thereto by a stud 53. This disposes the flexible conductor 16 on the outer side of the leg of the wearer. The clamping portion 32 is provided with a guide pin 52 protruding from the inner end thereof and which slidably engages in an opening 54 in the inner end of the clamping portion 33. The guide pin 52 together with the tightening screw 38 retain the clamping portions 32 and 33 in alignment and prevent canting thereof.

Instead of the grounding member 15, a grounding member shown in Figs. 9 and 10 of the drawings may be utilized which similarly consists of oppositely disposed clamping portions 55 and 56 having upwardly extending inwardly directed outer ends 57 and 58 respectively which are adapted to clamp over the outer edges of the shoe sole similar to the grounding member 15. in this form however, the clamping portion 55 is formed with a longitudinally extending opening 59 which is aligned with a longitudinally extending opening 60 in the clamping portion 56. The openings 59 and 6-9 are right and left hand threaded and are engaged by a tightening screw 63 which is threaded at its ends to engage in the threaded openings in the clamping portions 55 and 56 for adjusting the clamping portions toward and away from each other. Adjacent the opposite longitudinal edge the clamping portion 55 is provided with a guide pin 61 protruding from the inner end thereof and which slidably engages in an opening 62 in the inner end of the clamping portion 56. The guide pin 61 to gether with the tightening screw 63 retain the clamping portions 55 and 56 in alignment and prevent canting thereof. The clamping portions 55 and 56 are formed with rectangular slots 65 and 66 located centrally thereof and which open through the outer ends thereof and terminate in downwardly extending dove-tailed portions 67 similar to the formation of the slots 40 and 41 in the grounding member 15. Contact members 63 having dove tailed upper ends corresponding to the shape of the lower portions 67 of the slots 65 and 66 slidably fit the said slots respectively and protrude therefrom for engage ment with a supporting surface. The contact members 68 are engaged by springs 69 for tensioning the contact members to insure positive contact with the supporting surface. The contact members 68 are retained in position in the slots'by cross pins 71.

Another form of grounding member, such as the grounding member 72 shown in Figs. l1 to l3 inclusive of the drawings may be employed in place of the aforesaid grounding members. The grounding member 72 is permanently aflixed to the under side of the outer sole D immediately in front of the heel E of a shoe, boot, overshoe and the like as shown in Figs. ll and 13 of the drawings. As illustrated, the grounding member 72 consists of a metallic block 73 having a generally flat upper face 74 adapted to fit tightly against the under side of the outer sole D and which is formed with a forward projection '75 extending laterally across the shoe sole from one side edge to the other thereof. The metallic block is secured to the shoe by rivets 77 extending through the forward projection 75 with the inner ends of the rivets extending through and anchored to the outer sole D. The block 73 is also provided with a tapered projection 78 adapted to engage in a transversely extending notch 79 at the juncture of the heel with the outer sole which together with the rivets 77 securely hold the block 73 in position against the under side of the outer sole D. The block 73 is formed with a rectangular shaped slot 80 which opens through the opposite sides thereof and which terminates in a downwardly extending dove-tailed portion 81 opening through the lower face thereof. A contact member 82 having a correspondingly shaped dove-tailed upper end slidably fits the slot 80 and protrudes therethrough for engagement with a supporting surface. A spring 76 tensions the contact member into engagement with the supporting surface.

The grounding member may be formed as a part of a shoe as embodied in the form shown in Figs. 14 and and in the form shown in Figs. 16 and 17. In the form shown in Figs. 14 and 15, a shoe indicated by the reference character F is provided with a metallic plate 83 secured to the shoe sole G thereof adjacent the heel H. The plate 83 is formed with an upwardly extending apertured lug 84 at the outer end thereof which is adapted to receive therethrough the lower end of the conductor section 19 of the flexible conductor 16. The plate 83 is secured to the under side of the sole G of the shoe F by a plurality of longitudinally spaced rivets 85 extending therethrough and connected at their inner ends with a conductive strip 86 which is secured to the inside face of the sole G of the shoe. A plurality of contact members 87 extend through openings in the shoe sole G centrally thereof with the outer ends thereof adapted to engage a supporting surface for carrying off static charges and with the inner ends of said contact members in engagement with the conductive strip 86. The conductive strip 86 is also connected with a conductive strip 88 embedded in the heel H and which is in engagement with contact members 89 protruding through the heel of the shoe with the outer end thereof adapted to engage a supporting surface. In order to protect the wearer the shoe is provided with an insulating inner-sole 90 covering the strip 86 and the entire inner face of the shoe sole G.

In the form of grounding member illustrated in Figs. 16 to 18 inclusive of the drawings, the shoe indicated by the reference character I is provided with a metallic plate 92 similar to the plate 83 and which is formed with an apertured lug 93 adapted to engage with the conductor section 19 of the flexible conductor 16. In this form of grounding member the plate 92 is secured to the sole K of the shoe by means of rivets 94 and underlying the sole K of the shoe as well as the heel L are layers of conductive material such as a rubber sole 95 and a rubber heel 96 impregnated throughout with graphite or other conductive material so as to conduct electrostatic charges from the flexible conductor 16 to the ground. The rubber sole 95 extends between the plate 92 and the sole K of the shoe and is connected with the rubber heel 96 by a conductor 97.

In certain instances the grounding device would be used under conditions such as wet weather which might render a shoe conductive. Under such conditions the grounding device might endanger the wearer in the event that it came in contact with a charged electric wire. in order to overcome this condition the grounding device may be connected with a rubber overshoe or with a high boot which may be worn in wet weather without endangering the wearer. 1n the form of grounding member illustrated in Figs. 19 to 21 inclusive of the drawings, the rubber overshoe M is formed with a conductive layer overlying the sole and heel such as the rubber sole 99 and rubber heel 100 which are impregnated throughout with graphite or other conductive material and secured to the sole and heel respectively of the rubber overshoe M. An auxiliary heel 101 is secured to the conductive heel 100 and this auxiliary heel is apertured to receive a metallic contact member 102 which overlies a portion of the inner face of the auxiliary heel 101 and projects through an opening 103 therein for engagement with a supporting surface. The contact member 102 is formed with a lateral extension 104 which projects through the side of the heel and has the conductor section 19 of the flexible conductor 16 affixed thereto.

The boot N illustrated in Figs. 22 to 24 inclusive is also adapted to be used in wet weather which would insulate the leg of the wearer. The boot is provided with a circular grounding member 107 which is secured in an opening 108 in the heel P of the boot by means of screws 109 engaging through the heel with the inner ends thereof anchored in the plate 107. One of the screws 109 also extends through a side plate 110 which is adapted to be connected with the conductor section 19 of the flexible conductor 16 as illustrated in the form shown in Figs. 1 to 8 inclusive of the drawings.

In connection with the overshoe M shown in Fig. 19 of the drawings, the auxiliary heel 101 may be secured to the overshoe in any desired manner and the same may be releasably secured thereto as illustrated by the spring clips 112 which engage over the side edges of the heel of the overshoe.

The grounding device is also applicable for use in connection with articles of foot covering adapted to be worn by nurses and doctors in operating rooms and the like and when administering or handling anesthetics which might ignite by an electrostatic spark, the article of foot covering being of a material which may be periodically cleaned or sterilized to render the same antiseptic. As illustrated, the article of foot covering 115 is a fabric boot adapted to be worn over the shoe and which is provided with a rear opening 115 and tie-strings 117 and 118 connected to the opposite upper portions 119 and 120 thereof for constricting the top thereof so as to tighten the same about the ankle of the wearer.

The article of foot covering 115 is preferably made of flexible fabric such as cotton duck, canvas and the like which is coated or impregnated with a conductive material such as finely divided graphite, carbon and the like mixed with a liquid bonding vehicle having a rubber base, synthetic plastic pyroxlin base, or synthetic resinous base, which impregnation or coating extends completely over the outer face of the bottom wall 121 thereof and over the side wall 120 and in engagement with an eyelet 122 extending through the side wall 120 which is connected with a grounding device 123 for conducting electrostatic charges from the body of the wearer to the ground. The grounding device 123 includes a leg encircling member 124 similar to the leg encircling member 11 in the previous form of the invention, a tensioning device 125 similar to the tensioning device 18 in the previous form of the invention and a resistor 126 similar to the resistor 17 in the previous form of the invention and which are connected together by chain conductor sections 127, and 129. A buttonhole is provided in the side wall 120 above the eyelet 122. This permits of the lower portion of the grounding device 123 extending downwardly within the article of foot covering and the conductor section 127 extending through the buttonhole to engage the eyelet 122. When so arranged, the lower portion or cuff of the trousers of the wearer may extend into the upper portion of the article of foot covering which is tightened thereabout by the tying of the tie-strings 117 and 118. In order to prevent the wearer receiving a shock in the event the article of foot covering comes in contact with a high tension conr d ductor, a protective ply of insulation material 131 is secured at its edges to the inner face of the side wall 120 in covering relation with the eyelet 122 and buttonhole 130 with the upper edge thereof open to permit of the insertion of the conductor section 127.

The article of foot covering may have an outer layer or covering 132 of cotton duct, canvas and the like extending over the bottom wall 133 thereof and partially over the opposite side walls 134 and 135 of the fabric boot indicated generally by the reference character 136 as shown in Figs. 27 and 28 of the drawings. The said outer layer 132 is coated or impregnated with a conductive material such as finely divided graphite, carbon and the like mixed with a liquid bonding vehicle as hereinbefore set forth so as to render the same conductive of electrostatic charges. The said outer covering 132 is secured to the article of foot covering 136 in any desired manner such as by stitching 137 and the upwardly extending portion 138 of the covering is provided with an eyelet 139 for engagement by a grounding device similar to the grounding device 123 in the previous form of the invention. If desired, the covering 132 may have an auxiliary sole 140 of similar material and similarly impregnated throughout with the conductive material and secured to the under side thereof as illustrated in Fig. 29 of the drawings by stitching 141 or any other desired means. This sole provides a durable tread portion so as to permit of the article of foot covering being worn without shoes. The article of foot covering 136 is also provided with a buttonhole 142 located above the eyelet 139 and with a ply of insulation material 143 secured at its edges to the inner face of the side Wall in covering relation with the eyelet 139 and buttonhole 142 to permit of the grounding device extending into the article of foot covering as hereinbefore described.

The metallic parts such as the grounding member in the several forms of the invention and the exposed parts of the flexible conductor and tensioning device and other exposed parts are made of non-sparking metal such as brass or equivalent alloy so as to prevent the emission of sparks which might ignite combustible material. It is to be understood that ferrous metals are avoided since such metals will emit sparks when striking flint and the like.

What is claimed is:

1. In a body grounding device, a flexible conductor, a leg encircling member for engagement about the leg of the wearer adjacent the knee and connected to the upper end of the flexible conductor and having a metallic plate adapted to contact the leg of the wearer, a conductive grounding member carried by an article to be worn on the foot and exposed on the under side thereof for engagement with a supporting surface, said grounding member being connected to the lower end of the flexible conductor for conducting electrostatic charges received from the body of the wearer to the supporting surface, an expandable and contractable tensioning device forming a part of said flexible conductor and consisting of telescopically associated tubular sections connected together by a coiled spring arranged therein for maintaining said flexible conductor taut and permitting of the elongation and contraction thereof with the movement of the leg of the wearer in walking, and an insulated resistance forming a part of said flexible conductor located adjacent the grounding member in overlying relation with the article worn on the foot of the wearer for preventing high electrical charges passing to the leg of the wearer through the flexible conductor.

2. In a body grounding device, a flexible conductor, a

leg encircling member for engagement about the leg of wearer adjacent the knee and connected to the upper end of the flexible conductor and having a metallic plate adapted to Contact the leg of the wearer, a conductive grounding member carried by a shoe and exposed on the under side thereof for engagement with a supporting surface, said grounding member being connected to the lower end of the flexible conductor for conducting electrostatic charges received from the body of the wearer to the supporting surface, an expandable and contractable tensioning device forming a part of said flexible conductor for maintaining said flexible conductor taut and permitting of the elongation and contraction thereof with the movement of the leg of the wearer in walking, an insulated resistance forming a part of said flexible conductor located adjacent the grounding member in overlying relation with the shoe of the wearer for preventing a high electrical charge passing to the leg of the wearer through the flexible conductor, said grounding member including oppositely disposed metallic clamping members having upwardly extending ea'rs adapted to engage the sole of the shoe, a screw having right and left-hand threaded ends engaging in correspondingly threaded openings in said clamping members for tightening the members on the shoe and said clamping members having slots opening through the lower faces thereof and grounding elements located in said slots with the lower ends thereof protruding therethrough for engagement with the supporting surface, and springs tensioning said grounding elements into outward position.

3. In a body grounding device, a flexible conductor, a leg encircling member adapted to engage about the leg of the wearer adjacent the knee and having a conductor element in conductive engagement with the leg of the wearer and connected to the upper end of the flexible conductor, a conductive grounding member carried by an article to be worn on the foot and exposed on the under side thereof for engagement with a supporting surface, said grounding member being connected to the lower end of the flexible conductor for conducting electrostatic charges received from the body of the wearer to the supporting surface, an expandable and contractable tensioning device forming a part of said flexible conductor for maintaining said flexible conductor taut and permitting of the elongation and contraction thereof with the movement of the leg of the wearer in walking, and an insulated resistance forming a part of said flexible conductor located adjacent the grounding member in overlying relation with the article worn on the foot of the wearer for preventing high electrical charges passing to the leg of the wearer through the flexible conductor.

4. In a body grounding device, a flexible conductor, a leg encircling member for engagement about the leg of the wearer adjacent the knee and connected to the upper end of theflexible conductor and having a conductive element adapted to contact the leg of the wearer, an article to be worn on the foot of the wearer having a conductive portion exposed on the under side thereof for engagement with a supporting surface, said grounding member being connected to the lower end of the flexible conductor for conducting electrostatic charges received from the body of the wearer to the supporting surface, an expandable and contractable tensioning device forming a part of said flexible conductor for maintaining said flexible conductor taut and permitting of the, elongation and contraction thereof with the movement of the leg of the wearer in walking, and an insulated resistance forming a part of said flexible conductor located adjacent the grounding member in overlying relation with the article to be worn on the footfor preventing high electrical charges passing to the leg ofthe wearer through the flexible conductor.

References Cited in the file of this patent UNITED STATES PATENTS 

